This application relates to a smoothing device for rotation of propeller of boat propulsion machine and more particularly to an improved device for preventing vibration transmission in a marine outboard drive.
As is well known, marine propulsion units such as outboard motors or inboard-outboard drives are caused to propel the associated watercraft over a wide variety of speeds and varying conditions. Normally, a reciprocating engine or engine having intermittent firing is employed as the power plant for driving the drive shaft and propeller regardless of whether the marine drive is an outboard motor per se or an inboard-board unit. When operating at low speeds, the intermittent firing of the power unit gives rise to intermittent power impulses to the drive shaft and, accordingly, the propeller shaft. Such intermittent power pulses give rise to vibrations which can be transmitted back to the associated watercraft and also gives rise to fluctuations in torque of the driving propeller that can cause oscillations of the boat about an axis defined by the outboard drive steering shaft.
It is, therefore, a principal object of this invention to provide an improved device for smoothing the pulses of a marine outboard drive.
It is a further object of this invention to provide an improved vibration damping coupling.